SMART works well as a Marin-Sonoma train, but it has a lot of shortcomings, too. Once it's up and running, it needs to look beyond Cloverdale-Larkspur.
It's 2030, and SMART is a smashing success. Despite the best efforts of rail opponents throughout the construction of both Phase One and Phase Two, SMART has far surpassed ridership expectations and is the backbone of Marin and Sonoma's transportation systems.

That, at least, is what I hope I'll get to write about in my late 40s. Despite its flaws, and they are manifold, SMART is a good project. This is especially true for the commuters from Sonoma to Marin who constitute 39% of Sonoma's commuting workforce. Yet for Marinites, SMART is only a partial solution. Far more Marin commuters work in San Francisco than in Sonoma, and this will be just as true when SMART is fully built as it is now. So how might SMART expand to serve areas outside Marin? Here are a few of the options I've seen floated around.

Run BART along SMART tracks, or vice versa. This plan sounds good, but it is technically impossible. BART runs on a different track width than SMART - Indian Gauge for BART, Standard Gauge for SMART. BART tracks would need to be constructed from scratch along 101, and SMART could not operate on them. If people are complaining how expensive SMART is, they'd surely balk at a project with more than 10 times the cost. Back of the envelope cost: $500 million/mile, or $6-35 billion, depending on how far north BART goes.

Run SMART across the Golden Gate Bridge to the Transbay Terminal. This plan would be a partial resurrection of the original BART plan, which called for the train system to run north to Ignacio. In its place, SMART would have to reconstruct tracks south of Larkspur, reconfigure the bottom deck of the Golden Gate Bridge, and build new tracks out from the Bridge. Once the system reached San Francisco, the system would get far trickier and far more expensive. SMART's trains couldn't run on the streetcar tracks along the Embarcadero for a number of reasons, such as incompatible stations and the safety of mixing streetcars and regular trains, so new tracks would need to be built through a dense, urban area already well-served by transit. In total, 16.5 miles of new track would need to be reconstructed or built. Back of the envelope cost: $8 billion+.

Run SMART across the Richmond-San Rafael Bridge to the nearest BART station. This concept makes sense on paper: little new rail would be required, as the lines already exist on the Richmond side. SMART would principally run through an industrial area, so this alignment would enhance the value of the line for freight. Doing this would require reconstructing the bridge's third lanes to handle train traffic. CalTrans is resistant to the idea of bicycles using that lane and would surely oppose running tracks along the bridge as well. As well, it would not help Marinites get to work so much as it would help others get to their jobs in Marin: by 2030, only 11,000 Marinites will commute to the East Bay while 32,000 East Bay residents will commute to Marin. Back of the envelope cost: $2 billion. (Compultense has a fantasy map with this alignment.)

All these plans have some heavy drawbacks. The isolation that makes Marin so fantastic hampers exercises such as this. So is there a way to improve connectivity without doing something with such high barriers? To some degree, yes.

As it currently stands, the Larkspur SMART station will be built 0.4 miles away from the Terminal, forcing a 15 minute walk through extremely pedestrian-unfriendly territory: a bus depot, two parking lots, a barren pedestrian bridge over an overbuilt Sir Francis Drake Boulevard, and another parking lot. This makes the total trip from SMART to San Francisco at least 55 minutes long - the maximum most people are willing to travel. Improving the space between the SMART station and the Ferry to be more pedestrian-friendly would ease the walk, and operating a shuttle would cut down on walking time.

There are no good, inexpensive ways to utilize SMART outside of its already described corridors unless Marin is willing to foot a much, much larger bill. Given the opposition SMART has received already, I cannot imagine support building for a further expansion without a major shift in thinking about transit in the County.